Recently, terminals for providing various types of information, for example, have been installed in public places and commercial facilities such as hospitals, museums, libraries, tourist resorts, and stations. Display apparatuses installed in these public places and commercial facilities require a large screen capable of displaying much information.
As one method for realizing a large screen, a method for disposing a plurality of display apparatuses horizontally and vertically has been proposed (for example, see Patent Document 1).
When a plurality of terminals are disposed in this manner, all display apparatuses are connected in a daisy chain or other display apparatuses are connected to a master device. Then, each display apparatus receives a video signal and a control signal output from a processing apparatus for controlling each display apparatus via each connection unit. As communication between the processing apparatus and the terminals and between the display apparatuses, for example, communication by universal asynchronous receiver/transmitter (UART), communication by an inter-integrated circuit (I2C) bus, and communication by a local area network (LAN) are used.
For example, when a plurality of display apparatuses are connected through LAN cables, each display apparatus has a physical layer circuit unit that controls a physical layer and a logical layer circuit unit that controls a logical layer. The physical layer circuit unit, for example, converts a logical signal into an electrical signal. The logical layer circuit unit, for example, interprets a media access control (MAC) address or the like from information of a transmitted MAC frame. The display apparatuses connected in the daisy chain have a plurality of LAN ports to which LAN cables are connected and have a physical layer circuit unit for each LAN port.
In addition, recently, reduction of power consumption during standby has been required. Thus, when, for example, a video signal and a control signal are not input to a plurality of display apparatuses, each display apparatus is controlled in a standby state. Here, the standby state refers to a state in which functional units other than circuits necessary for restoring power-supply of the display apparatus are controlled in a standby state. Each display apparatus causes each circuit to be shifted to the standby state by detecting an operation unit provided in at least one display apparatus among a plurality of connected display apparatuses has been operated in the standby state.
In addition, the processing apparatus which controls the plurality of display apparatuses sets each display apparatus to a power-supply ON state by transmitting an instruction for shifting from the standby state to the power-supply ON state to each display apparatus using a wake-on LAN (WOL) function of the LAN.